Fetal Neurology Clinic, Ultrasound in ObGyn Unit, Wolfson Medical Center, Holon, Israel.
Affiliated to the Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Ultrasound Obstet Gynecol. 2019 Mar;53(3):390-395. doi: 10.1002/uog.19034. Epub 2019 Jan 31.
Prenatal diagnosis of midbrain-hindbrain (MB-HB) malformations relies primarily on abnormal size and shape of the cerebellum and retrocerebellar space, particularly 'open fourth ventricle' (4V), the most common indicator of MB-HB malformations. The aim of this study was to present the fourth ventricle index (4VI), and to evaluate its role as a marker for severe vermian dysgenesis/agenesis in cases without open 4V.
This was a prospective cross-sectional study of patients with singleton low-risk pregnancy at 14 + 1 to 36 + 6 gestational weeks presenting between May 2016 and November 2017 for routine ultrasound examination. Axial images of the fetal 4V were obtained and the 4VI was calculated as the ratio between the laterolateral and the anteroposterior diameters. Reference ranges were constructed and retrospectively collected values from 44 fetuses with confirmed anomalies involving severe vermian dysgenesis/agenesis (Joubert syndrome and related disorders, rhombencephalosynapsis, cobblestone malformations and cerebellar hypoplasia) but without open 4V were compared with the normal values.
In total, 384 healthy fetuses were enrolled into the study, from which reference ranges were produced, and 44 cases were collected retrospectively. The 4VI in the normal fetuses was always > 1. In affected fetuses, it was always below mean -2 SD and < 1.
The 4VI is a sonographic marker for severe fetal vermian dysgenesis/agenesis in the absence of an open 4V. It may be incorporated easily into the routine brain scan; 4VI < 1 indicates a need for dedicated fetal neuroimaging for diagnosis and prenatal counseling. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.
中脑-后脑（MB-HB）畸形的产前诊断主要依赖于小脑和后脑空间的异常大小和形状，特别是“开放的第四脑室”（4V），这是 MB-HB 畸形最常见的指标。本研究旨在介绍第四脑室指数（4VI），并评估其作为无开放 4V 情况下严重蚓部发育不良/发育不全的标志物的作用。
这是一项前瞻性的横断面研究，纳入了 2016 年 5 月至 2017 年 11 月期间因常规超声检查而就诊的 14+1 至 36+6 孕周单胎低危妊娠的患者。获取胎儿 4V 的轴向图像，并计算 4VI 作为后外侧和前后直径的比值。构建参考范围，并回顾性收集 44 例涉及严重蚓部发育不良/发育不全（Joubert 综合征及相关疾病、后脑联合、鹅卵石畸形和小脑发育不全）但无开放 4V 的胎儿异常的回顾性值，并与正常值进行比较。
共有 384 例健康胎儿纳入本研究，得出参考范围，并回顾性收集 44 例。正常胎儿的 4VI 始终>1。在受影响的胎儿中，它始终低于均值-2SD 且<1。
4VI 是无开放 4V 时严重胎儿蚓部发育不良/发育不全的超声标志物。它可以很容易地纳入常规脑扫描中；4VI<1 表明需要进行专门的胎儿神经影像学检查以进行诊断和产前咨询。版权所有 © 2018 ISUOG。由 John Wiley & Sons Ltd 出版。
